This invention pertains to a polishing pad comprising a region that is at least translucent to light, and a method of producing and using such a polishing pad.
In polishing the surface of a substrate, it is often advantageous to monitor the polishing process in situ. One method of monitoring the polishing process in situ involves the use of a polishing pad having an aperture or window. The aperture or window provides a portal through which light can pass to allow the inspection of the substrate surface during the polishing process. Polishing pads having apertures and windows are known and have been used to polish substrates, such as the surface of semiconductor devices. For example, U.S. Pat. No. 5,605,760 (Roberts) provides a pad having a transparent window formed from a solid, uniform polymer, which has no intrinsic ability to absorb or transport slurry. U.S. Pat. No. 5,433,651 (Lustig et al.) discloses a polishing pad wherein a portion of the pad has been removed to provide an aperture through which light can pass. U.S. Pat. No. 5,893,796 and 5,964,643 (both by Birang et al.) disclose removing a portion of a polishing pad to provide an aperture and placing a transparent polyurethane or quartz plug in the aperture to provide a transparent window, or removing a portion of the backing of a polishing pad to provide a translucency in the pad.
Still, there remains a need for effective polishing pads having translucent regions and efficient methods for their production and use. The invention provides such a pad, as well as methods of its production and use. These and other advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
The present invention provides a polishing pad comprising a region that is at least translucent, wherein the translucent region comprises a matrix polymer and a filler. The present invention further provides a method for producing a polishing pad comprising a region that is at least translucent, which method comprises (a) providing a porous matrix polymer, (b) filling at least a portion of the pores of the matrix polymer with a filler to provide a region that is at least translucent, and (c) forming a polishing pad comprising the region that is at least translucent. A method of polishing a substrate, particularly a semiconductor substrate, comprising the use of the polishing pad of the present invention also is provided herein.